Blood oxygenator

ABSTRACT

A blood oxygenator is provided with a preformed defoaming member of open-cell sponge material of synthetic plastic disposed in the defoaming chamber in series between the oxygenating chamber and the blood reservoir chamber of the oxygenator. Spaces are provided between the defoaming member and the upper and lower walls of the defoaming chamber to produce a reduced resistance to the flow of gas and blood. A fine mesh filter and funnel are connected to the defoaming chamber to gently transfer and filter blood flowing to the reservoir.

United States Patent 1191 1111 Talonn [45] Nov. 11, 1975 [5 BLOODOXYGENATOR 3.747.769 7/1973 Brumfield 1. 210/010. 23 x 3. 27. 6O 8 974 Bl' 1 1 1 1 1 v 123 258.5 [75] Inventor: Daniel A. Talonn. UnlversltyCll). #1 z s a al 1758 S MO [73] Assignee: Sherwood Medical IndustriesInc., 'f 'l' f Y Richman S L i M Assistant Eran1merM1chasel Si Mzligclgb w H Arr' ,A I. 'F'-t '.arer; "am 1221 Filed: on. 15. 1973 R gf 'j f q1211 Appl. NO; 406,455 ABSTRACT [52] us. Cl 23/2;8 Dig/DIG 3 A bloodoxygenator is provided with a preformed de- [511 Int B U foaming memberof open-cell sponge material of syn- [58] Field pig/DIG thetic plasticdisposed in the defoaming chamber in b d series between the oxygenatingchamber and the blood reservoir chamber of the oxygenator Spaces are[56] References cued provided between the defoaming member and the upperand lower walls of the defoaming chamber to UNITED STATES PATENTSproduce a reduced resistance to the flow of gas and 4/1963 Broman 1blood A fine mesh filter and funnel are onne ted t x g $72 the defoamingchamber to gently transfer and filter omp 1ns v v 1 3.6l5.238 10/1971Bentl 23/2585 blood flomng to the reserolr' 3.729.377 4/1973 Leonard23/2585 8 Claims, 10 Drawing Figures US. Patent Nov.11, 1975 Sheet10f23,918,912

U.S. Patent Nov. 11, 1975 Sheet 2 012 3,918,912

BLOOD OXYGENATOR BACKGROUND OF THE INVENTION This invention relates toblood oxygenators and more particularly to oxygenators of the bubbletype which are used in extracorporeal circulation systems which assumethe functions of the heart and lungs during cardiac and other surgery.

Oxygenators of this type generally include an oxygenating chamber inwhich blood and gas are mixed to produce a blood foam, a defoamingchamber containing a defoaming member, and a reservoir chamber forreceiving the defoamed oxygenated blood for return to the arterialsystem of the patient. Obviously, undisolved gas and gas bubbles must beeliminated from the oxygenated blood before returning it to the patient.While the defoaming member removes most of the gas from the oxygenatedblood foam, some past constructions tended to produce blood churning andblood bubbles due to the transfer of blood from the downstream end ofthe defoaming chamber to the reservoir chamber. Even small heightsbetween the lowemiost tip of the defoaming chamber and the reservoirsometimes caused blood to splash and trap air with the danger that suchtrapped air may enter the arterial system of the patient. Pastconstructions have not been entirely satisfactory in transfering theblood from the defoaming chamber to the pool of blood in the reservoirwithout introducing air bubbles into the blood, or they have failed toprovide means for eliminating such bubbles that might occur as a resultof the transfer of blood to the reservoir.

SUMMARY OF THE INVENTION Accordingly, it is an object of the presentinvention to provide a blood oxygenator with means to substantiallyensure against the possibility of air being trapped in the bloodcontained in the blood reservoir.

In accordance with one form of the present invention a funnel and filterassembly in disposed at the downstream end of the defoaming chamber ofan oxygenator with the lower ends of both submerged in the blood withinthe blood reservoir.

These as well as other objects and advantages of the present inventionwill become apparent from the following detailed description andaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical cross-sectionalview of an oxygenator in accordance with a preferred embodiment of thepresent invention;

FIG. 2 is an enlarged cross-sectional view taken along line 2-2 of FIG.1;

FIG. 3 is an enlarged cross-sectional view taken along line 3-3 of FIG.1;

FIG. 4 is an enlarged side view of the defoaming member of theoxygenator of FIG. 1;

FIG. 5 is a cross-sectional view taken along the line of 5-5 of FIG. 4;

FIG. 6 is a bottom view of the defoaming member of FIG. 4;

FIG. 7 is an enlarged view of a sheet of material from which the funnelof FIG. I is formed;

FIG. 8 is a side view of the funnel formed by folding the sheet of FIG.7;

2 FIG. 9 is an enlarged plan view of a sheet of material from which thefilter of FIG. 1 is formed; and

FIG. 10 is an enlarged side view showing the funnel and filter assemblyused in the oxygenator of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings,and particularly to FIGS. 1-3, there is shown an oxygenator 10 of thebubble" type which is adapted for connection in an extracorporealcirculation system of a patient during surgery. The oxygenator 10includes a pair of translucent sheets 12 and 14 of a synthetic plasticmaterial, such as thermoplastic polyurethane sheet material. The sheetsare heat sealed or welded together along a predetermined path forming aseam 16 which appears in cross-section in FIG. 1. Seam 16 forms anelongated defoaming chamber 18 and a blood reservoir chamber 20. Thereservoir chamber has its upper portion connected in fluid communicationwith the defoaming chamber 18, and is provided with an outlet 22 at thebottom adapted for connection through a suitable blood pump to thearterial system of the patient. In the illustrated embodiment, a bloodoxygenating chamber 24 is provided by a seperate open ended plastic tube26 formed of the same material as sheets 12 and I4 and heat sealed atits upper end by a peripheral seam 28 to the upper end portion of thedefoaming chamber 18.

An oxygenating gas diffuser 30 is disposed in tube 26 in fluid tightsealing engagement with its walls. A plastic tube 32 has one endconnected to the diffuser 30 and is adapted to be connected at the otherend with the venous system of the patient for supplying venous blood tooxygenating chamber 24. A plastic tube 34 has one end connected to thediffuser 30 and is adapted to be connected at the other end to a sourceof oxygenating gas. Diffuser 30 has an internal chamber connected withtube 34, and an upper plate 36 at the top of the chamber. Plate 36 ispreferably formed with a plurality of small holes (not shown) throughwhich the oxygenating gas must bass. The tube 32 extends through theplate 36 so that the blood will flow over the plate. In this way, thegas will be evenly distributed in the venous blood and cause blood foamto rise in the oxygenating chamber 24.

Disposed in the defoaming chamber 18 is a preformed defoaming member 38for removing bubbles and undissolved gas from the blood. A funnel andfilter assembly 40 is connected to chamber 18 at the downstream end forgently transferring oxygenated blood from chamber 18 to the reservoir 20and removing any gas bubbles that might flow out of chamber 18, as willbe fully described hereafter. The defoaming chamber 18 is provided witha vent 42 in the upper wall adjacent the downstream end of defoamingmember 38 to permit the escape of excess and undissolved gas to theatmosphere.

The defoaming chamber 18 and member 38 are the subject matter of anapplication Ser. No. 406,501 filed on the same day as this applicationand having the same assignee.

Referring now also to FIGS. 4-6, defoaming member 38 is a unitary memberformed of a synthetic plastic sponge material of open-cell construction.Preferably, it is formed of a polyurethane sponge material and coatedthroughout with an anti-foam agent, such as a silicone grease wellknownfor this purpose. The defoaming member is shown elongated and having anupper wall 44 which is flat and parallel with the longitudinal axis ofthe member, and a bottom wall 45 having a pair of arcuate recesses 46and 48. As seen in FIG. 5, the upper and lower walls 44 and 45 arebeveled so that the overall cross-sectional configuration of member 38is somewhat eliptical as is the defoaming chamber I8 as seen in FIG. 2.Also, the downstream tip, indicated at 50, is tapered. With thisconfiguration the member 38 fits snugly within the defoaming chamber 18with tip 50 within the funnel and filter assembly 40 as seen in FIG. I.

When the defoaming member 38 is in the oxygenator of FIG. 1, therecesses 46 and 48 provide radial spaces between the bottom wall ofchamber 18 and member 38 to provide free flow portions in the blood flowpath to increase the rate of blood flow through the defoaming chamber.The defoaming member 38 engages the bottom wall of chamber 18, on eachside of each of the recesses so that any gas flowing with the blood inthese spaces will flow through defoaming member 38 and be released fromthe blood. The upper wall of chamber 18 is defined by an undulatingportion of the seam 16 producing three indentations 52 which providelongitudinally spaced, radial spaces 54 and 56 between the upper wallsof the chamber 18 and defoaming member 38 which enhance the flow ofexcess or undisolved gas through the defoaming chamber 18 to the vent 42to reduce operating pressures and improve the defoaming action.

The funnel and filter assembly 40 includes a funnel 58 of syntheticplastic, such as polyurethane, and a pocket-like filter member 60 whichis formed of a suitable fine-mesh cloth material such as a syntheticplastic, perferably nylon, for example, 100 micron nylon filtrationcloth. FIG. 7 shows the pattern or cutout 58 which is folded to form thefunnel shown in FIG. 8, the funnel having a seamless bottom wall andbeing generally triangular in side view. Similarly, a cut-out or pattern60 shown in FIG. 9 is folded to form the pocket filter seen in FIG. 10.

The cutouts S8 and 60 may be placed in face-to-face relation and thesides 62 and 64 of the cutout 58 heatsealed to the sides 66 and 68,respectively, of the filter pattern 60 to provide a circumferential heatseam 70 which is partially seen in FIG. 10. The two connected cutoutsare then folded and the opposed free edges of the filter pattern areheat sealed together by a heat seam indicated at 72 in FIG. to form thepocket which is open only at the top at seam 70. Seam 72 also seals, theopposed relatively small corners 73 and 74 (FIG. 7) of the funneltogether. Thus, the funnel 58 is completely received in the filter 60.Before heat sealing the two plastic sheets 12 and 14 to form thechambers I8 and 20, the funnel and filter assembly 40 is heat sealed tothe sheets by a circumferential seam partially shown in FIG. I at 75which seals seam 70 to the downstream end of the defoaming chamber 18.

As seen in FIG. 1, the bottom wall of the defoaming chamber 18 isinclined downwardly from the oxygenating chamber 24 toward the reservoir20. Likewise, the lower wall of the funnel 58 is inclined downwardlytoward the reservoir, it being inclined somewhat less than that of thebottom wall of chamber 18 so as to provide a substantially smoothconnection with chamber 18 and gently transfer blood to the reservoir20.

Before connecting the oxygenator 10 for operation, a predeterminedamount of priming blood is introduced into the reservoir 20, such asthrough a port 76. the reservoir 20 is filled with priming blood up to alevel indicated by the indicia or arrow 77 provided on the oxygenator sothat the lower tips of the funnel 58 and filter extend into the bloodslightly below the blood level indicated also by line 78 in FIG. I. Inthis way, the funnel 58 prevents blood from dripping from the walls ofthe defoaming chamber and from the defoaming member into the pool ofblood in the reservoir, and thereby avoids splashing and entrapment ofgas. While the funnel gently transfers oxygenated blood from thedefoaming chamber 18 to the blood in the reservoir, the filter 60, whichis downstream of the funnel and surrounds it, removes any bubbles thatmight reach it or that might be created by blood leaving the funnel. Thefilter will also remove any debris or blood clots.

In operation, venous blood flows through tube 32 and over the diffuser30 and oxygenating gas flows from tube 34 producing a foam which risesin the oxygenating chamber 24. As the foam rises, carbon dioxide isreleased from the blood and oxygen is disolved in the blood to provide adesired oxygenation of the blood. The defoaming member 38 removesbubbles from the foam and allows gas and blood to pass through it. Gastends to rise in the defoaming member 38 so that some flows downwardlyalong the upper wall of the defoaming chamber 18 through spaces 54 and56 toward the vent 42, the spaces serving to lower the resistance to gasflow through chamber 18. The oxygenated blood and foam tend to flowdownwardly through the defoaming member to the lower wall of chamber 18.Blood flows along the lower wall with some blood able to flow throughthe free flow portions of the blood path formed by recesses 46 and 48,which lower the resistance to blood flow through the chamber 18 toobtain a desired relatively high rate of blood flow through theoxygenator. All of the blood flowing from chamber 18 flows into thefunnel 58 where it is gently transferred to the blood pool in reservoir20 and all of the blood from the funnel must flow through the filter 60before it is returned to the patient. As previously mentioned, anydebris, blood clots, or bubbles reaching the filter 60 will be removedand the gas from any bubbles released to the atmosphere by vent 42. Theoxygenated blood is, of course, returned to the arterial system of thepatient by way of outlet 22.

As seen in FIG. 3, the bottom inclined wall of the funnel 58 and itslower tip are spaced laterally from the sheets 12 and 14 and thispermits the blood that is flowing out of the funnel to readily circulatein the pool around the funnel tip and obtain good mixing of blood toavoid stagnant blood. With the lowermost ends of the funnel and filterspaced downstream of the defoaming member 38, the funnel provides achannel or path for the defoamed blood beyond the defoaming member.

While a preferred form of the invention has been described herein, itwill be apparent that various changes and modifications thereto may bemade without departing from the true spirit and scope of the inventionas defined in the claims which follow.

What is claimed is:

l. A blood oxygenator comprising an oxygenating chamber, means fordelivering venous blood and oxygenating gas to said oxygenating chamberfor producing foamed blood in said oxygenating chamber to oxygenate theblood, a reservoir for receiving oxygenated blood and having an outletfor discharging oxygenated blood, said reservoir being normally filledwith blood to an operating blood level, indicia means including 21visual mark in fixed relation to said chamber providing a visualindication of said operating blood level, defoaming means including adefoaming chamber connected between said oxygenating chamber and saidreservoir, and a defoaming member in said defoaming chamber for removinggas from said foamed blood, a funnel member connected to the downstreamend of said defoaming chamber and inclined downwardly toward saidreservoir with the lower end thereof disposed below said indicia meansto gently transfer blood from said defoaming chamber to said reservoir,said funnel member being disposed to receive and pass all of the bloodflowing from said defoaming means to said reservoir and said outlet, anda filter member extending below said lower end of said funnel and saidindicia means so that all of the blood flowing from said funnel memberto said reservoir and said outlet flows through said filter member.

2. The blood oxygenator of claim 1 wherein said funnel member extendsbeyond the lowermost end of said defoaming means.

3. The blood oxygenator of claim 1 wherein said funnel and filtermembers each has opposed side wall with the side walls of said funnelmember disposed between the side walls of said filter member.

4. The blood oxygenator of claim 1 wherein said reservoir has opposedside walls, and the lower end of said funnel member is spaced from theside walls of said reservoir.

5. The blood oxygenator of claim 4 wherein said filter member comprisesa pocket of fine mesh filtering material, and said funnel member isdisposed in and surrounded by said pocket.

6. The blood oxygenator of claim 5 wherein said funnel member and saidfiltering material are of synthetic plastic.

7. The oxygenator of claim 5 wherein said funnel member is a unitarysheet folded to provide a seamless bottom wall for transfering bloodfrom said defoaming chamber to said reservoir.

8. The oxygenator of claim 7 further including a pair of syntheticplastic sheet members predetenninately heat sealed along a seam todefine said defoaming chamber and said reservoir, and wherein saidfilter member is open only at the upper end thereof, said funnel memberhas an upper open end heat sealed to said upper end of said filtermember to provide a funnel and filter assembly open at the upper end,and said upper end of said assembly is heat sealed to said sheet membersat the lower end of said defoaming chamber.

1. A BLOOD OXYGENATOR COMPRISING AN OXYGENATING CHAMBER, MEANS FORDELIVERING VENOUS BLOOD AND OXYBENATING GAS TO SAID OXYGENATING CHAMBERFOR PRODUCING FOAMED BLOOD IN SAID OXYGENATING CHAMBER TO OXYGENATE THEBLOOD, A RESERVOIR FOR RECEIVING OXYGENATED BLOOD AND HAVING AN OUT LETFOR DISCHARGING OXYGENATED BLOOD, SAID RESERVOIR BEING NORMALLY FILLEDWITH BLOOD TO AN OPERATING BLOOD LEVEL, INDICIA MEANS INCLUDING A VISUALMARK IN FIXED RELATION TO SAID CHAMBER PROVICING A VISUAL INDICATION OFSAID OPERATING BLOOD LEVEL, DEFOAMING MEANS INCLUDING A DEFOAMINGCHAMBER CONNECTED BETWEEN SAID OXYGENERATING CHAMBER AND SAID RESERVOIR,AND A DEFOAMING MEMBER IN SAID DEFOAMING CHAMBER FOR REMOVING GAS FROMSAID FOAMED BLOOD, A FUNNEL MEMBER CONNECTED TO THE DOWNSTREAM END OFSAID DEFOAMING CHAMBER AND INCLINED DOWNWARDLY TOWARD SAID RESERVOIRWITH THE LOWER END THEREOF DISPOSED BELOW SAID INDICIA MEANS TO GENTLYTRANSFER BLOOD FROM SAID DEFOAMING CHAMBER TO SAID RESERVOIR, SAIDFUNNEL MEMBER BEING DISPOSED TO RECEIVE AND PASS ALL OF THE BLOODFLOWING FROM SAID DEFOAMING A MEANS TO SAID RESERVOIR AND SAID OUTLET,AND A FILTER MEMBER EXTENDING BELOW SAID LOWER END OF SAID FUNNEL ANDSAID INDICEA MEANS SO THAT ALL OF THE BLOOD FLOWING FROM SAID FUNNELMEMBER TO SAID RESERVOIR AD SAID OUTLET FLOWS THROUGH SAID FILTERMEMBER.
 2. The blood oxygenator of claim 1 wherein said funnel memberextends beyond the lowermost end of said defoaming means.
 3. The bloodoxygenator of claim 1 wherein said funnel and filter members each hasopposed side wall with the side walls of said funnel member disposedbetween the side walls of said filter member.
 4. The blood oxygenator ofcLaim 1 wherein said reservoir has opposed side walls, and the lower endof said funnel member is spaced from the side walls of said reservoir.5. The blood oxygenator of claim 4 wherein said filter member comprisesa pocket of fine mesh filtering material, and said funnel member isdisposed in and surrounded by said pocket.
 6. The blood oxygenator ofclaim 5 wherein said funnel member and said filtering material are ofsynthetic plastic.
 7. The oxygenator of claim 5 wherein said funnelmember is a unitary sheet folded to provide a seamless bottom wall fortransfering blood from said defoaming chamber to said reservoir.
 8. Theoxygenator of claim 7 further including a pair of synthetic plasticsheet members predeterminately heat sealed along a seam to define saiddefoaming chamber and said reservoir, and wherein said filter member isopen only at the upper end thereof, said funnel member has an upper openend heat sealed to said upper end of said filter member to provide afunnel and filter assembly open at the upper end, and said upper end ofsaid assembly is heat sealed to said sheet members at the lower end ofsaid defoaming chamber.